Deprecate packages:all:compiler and update default configs

Signed-off-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

etc/spack/defaults/darwin/packages.yaml

@@ -15,12 +15,11 @@
 # -------------------------------------------------------------------------
 packages:
   all:
-    compiler:
-    - apple-clang
-    - clang
-    - gcc
     providers:
+      c: [apple-clang, llvm, gcc]
+      cxx: [apple-clang, llvm, gcc]
       elf: [libelf]
+      fortran: [gcc]
       fuse: [macfuse]
       gl: [apple-gl]
       glu: [apple-glu]

etc/spack/defaults/packages.yaml

@@ -15,19 +15,18 @@
 # -------------------------------------------------------------------------
 packages:
   all:
-    compiler: [gcc, clang, oneapi, xl, nag, fj, aocc]
     providers:
       awk: [gawk]
       armci: [armcimpi]
       blas: [openblas, amdblis]
-      c: [gcc]
-      cxx: [gcc]
+      c: [gcc, llvm, intel-oneapi-compilers, xl, aocc]
+      cxx: [gcc, llvm, intel-oneapi-compilers, xl, aocc]
       D: [ldc]
       daal: [intel-oneapi-daal]
       elf: [elfutils]
       fftw-api: [fftw, amdfftw]
       flame: [libflame, amdlibflame]
-      fortran: [gcc]
+      fortran: [gcc, llvm]
       fortran-rt: [gcc-runtime, intel-oneapi-runtime]
       fuse: [libfuse]
       gl: [glx, osmesa]

etc/spack/defaults/windows/packages.yaml

@@ -15,8 +15,8 @@
 # -------------------------------------------------------------------------
 packages:
   all:
-    compiler:
-    - msvc
     providers:
+      c : [msvc]
+      cxx: [msvc]
       mpi: [msmpi]
       gl: [wgl]

lib/spack/spack/schema/packages.py

@@ -138,6 +138,15 @@
                     },
                     "variants": variants,
                 },
+                "deprecatedProperties": [
+                    {
+                        "names": ["compiler"],
+                        "message": "The packages:all:compiler preference has been deprecated in "
+                        "Spack v0.24, and is currently ignored. It will be removed from config in "
+                        "Spack v0.26.",
+                        "error": False,
+                    }
+                ],
             }
         },
         "patternProperties": {